<template>
  <div class="model">
    {{a}} <el-button @click="add">1</el-button>
  </div>
</template>

<script>
export default {
  model: {
    prop: "a",
    event: "change1"
  },
  props: {
    a: {
      type: Number,
      default: 0
    }
  },
  methods: {
    add() {
      this.a++
      this.$emit("change1",this.a)
    }
  },
  mounted() {
    console.log(this.$listeners)
  }
}
</script>

<style>

</style>